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Abstract

A novel on-chip spectrometer device using combined functionalities of a micro-ring resonator and a planar diffraction grating is proposed. We investigate the performance of this architecture by implementing it in a silicon-on-insulator platform. We experimentally demonstrate such a device with 100 channels, 0.1 nm channel spacing and a channel crosstalk less than -10 dB. The entire device occupies an area of less than 2 mm2. Based on our initial results we envision that this device enables the possibility of the realization of low-cost and high-resolution ultra-compact spectroscopy.

Figures (6)

(a). Micrograph of the spectrometer with ring. Note that the ring resonator’s drop port is used as input of the grating spectrometer. (b) Close-up view of ring resonator. c) Zoom in the diffraction grating. The teeth opposite to the grating facets are used to decrease back reflection. d) Close-up view of the spectrometer output waveguides.

(a). Theoretical ring resonator input to drop port transmission spectrum (in black) and transmission spectrum of DG spectrometer for different channels. b) Theoretical transmission spectrum for the combined ring and diffraction grating spectrometer. The small peaks are due to the overlap of the residual transmission from the DG spectrometer with the neighboring resonances.

(a). Cavity resonance width at 1500 nm as function of drop efficiency for different waveguide losses. (b). Transmission spectrum for a combined ring and DG spectrometer compared to the through port transmission level.

(a). Space serialization schematic. Multiple devices are concatenated, where each device transmission spectrum is spectrally shifted. (b). Time serialization schematic. Same device is used to make the measurements but with shifted spectral transmission at each measurement.

(a). Zoom-in of the transmission spectrum for waveguide 5 in Fig. 5. (b). Density plot of the transmission spectrum for a combined ring and diffraction spectrometer using a time serialization technique, where each horizontal line refers to a channel of the spectrometer.